Biology and biochemistry

Lactobacillus is Gram-positive (they retain crystal violet dye), facultative anaerobe (they can produce energy through glycolysis and fermentation when oxygen is not present). Lactobacillus is a member of the lactic acid bacteria group (its members convert lactose and other sugars to lactic acid).

Usage in humans

Effectiveness

Lactobacillus is a type of bacteria with multiple different species in the genus. Most Lactobacillus in humans are considered un-harmful. Lactobacilli live in the urinary, digestive and genital tracks of humans. Lactobacillus is possibly effective for preventing diarrhea in children, or a bacterial vaginal infections. However, it may be possibly ineffective for UTI's, lactose intolerance, and yeast infections. [5]

This article's factual accuracy is disputed. Please help to ensure that disputed statements are reliably sourced.(May 2015)

Probiotics and biotherapeutics

Some strains of Lactobacillusspp. and other lactic acid bacteria may possess potential therapeutic properties including anti-inflammatory and anti-cancer activities, as well as other features of interest. A study by researchers from the Beth Israel Deaconess Medical Center and UCLA in 2009 demonstrated the protective effects of some strains of these bacteria for anti-tumor and anti-cancer effects in mice.[6]

Lactobacilli can also be used to restore particular physiological balance such as in the vaginal eco-system.[7][8][9] Their role is (1) to physically protect the vaginal epithelium by building a thick layer separating the epithelium from pathogens, (2) to physiologically keep the balance of the vaginal ecosystem in maintaining the pH at ~4.5, and (3) generating hydrogen peroxide against pathogens. Lactobacilli are highly tolerant to low pH and can easily maintain low pH and protect the vaginal eco-system from Gram-negative and Gram-positive bacteria.

Food production

Some Lactobacillus species are used as starter cultures in industry for controlled fermentation in the production of yogurt, cheese, sauerkraut, pickles, beer, wine, cider, kimchi, cocoa, kefir, and other fermented foods, as well as animal feeds. The antibacterial and anti fungal activity of "Lactobacillus" rely on production of bacteriocins and low-molecular weight compounds that inhibits these microorganisms. [10]

Sourdough bread is made using a "starter culture," which is a symbiotic culture of yeast and lactic acid bacteria growing in a water and flourmedium. The bacteria metabolize sugars into lactic acid, which lowers the pH of their environment, creating a signature "sourness" associated with yogurt, sauerkraut, etc.

In many traditional pickling processes, vegetables are submerged in brine, and salt-tolerant lactobacillus species feed on natural sugars found in the vegetables. The resulting mix of salt and lactic acid is a hostile environment for other microbes, such as fungi, and the vegetables are thus preserved -- remaining edible for long periods.

Lactobacilli, especially L. casei and L. brevis, are some of the most common beer spoilage organisms. They are however essential to the production of sour beers such as Belgian Lambics and American Wild Ales, giving the beer a distinct tart flavor.

Dental caries

While streptococci family bacteria (e.g. Streptococcus mutans) are the main cause of tooth decay, other varieties of microbes can cause dental caries, but to a lesser extent. For example, although considered beneficial, some Lactobacillus species have been associated with dental caries. The Lactobacillus count in saliva has been used as a "caries test" for many years. This is one of the arguments used in support of the use of fluoride in toothpaste. Lactobacilli characteristically cause existing carious lesions to progress, especially those in coronal caries. The issue is, however, complex as recent studies show probiotics can allow beneficial lactobacilli to populate sites on teeth, preventing streptococci pathogens from taking hold and inducing dental decay.[11][12]

^Fijan, Sabina (2014). "Microorganisms with Claimed Probiotic Properties: An Overview of Recent Literature". International Journal of Environmental Research and Public Health11 (5): 4745–4767. ISSN1660-4601. doi:10.3390/ijerph110504745.